Process for producing bulk yarns from film strips



J. R. WHITE 3,177,557 PROCESS FOR PRODUCING BULK YARNS FROM FILM STRIPS April 13, 1965 Filed Jan. 22, 1964 FIGZ FIG.

FIG. 5

n// W @WN INVENTOR JAMES RUSHTON WHITE BY 0% ATTORNEY United States Patent Ofiice 3,177,557 Patented Apr. 13, 1965 3,177,557 PROCESS FOR PRDDUCING BULK YARNS FROM FILM STRIPS James Rushton White, Chapel Hill, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware Filed Jan. 22, 1964, Ser. No. 339,558 9 Claims. (Cl. 28-72) This invention relates to a simplified process for preparing bulky yarns from synthetic polymers. More specifically, it relates to the preparation of bulky yarns directly from molecularly oriented film strips.

Artificial filamentary materials are usually produced as continuous filaments. Yarns made from these continuous filaments are much stronger than spun staple yarns, but lack many of the desirable aesthetic qualities of the spun yarns. Because of their uniformity and smooth sur face, continuous filament yarns have less desirable tactile properties. The filaments lie close together in the yarn, and adjacent strands of continuous filament yarn in fabrics are closely spaced. This compactness makes for denser fabrics with less warmth and covering power per unit weight. Consequently, a large percentage of the total production of continuous filaments of synthetic material such as viscose rayon, cellulose acetate, nylon, poly(ethylene terephthalate), and poly(acrylonitrile) is cut into short lengths for spinning into staple yarns.

The production of yarn from staple fiber, both natural and synthetic, is a costly process. The conventional, widely used process involves a complex series of operations to align the fibers, combine'them into an elongated bundle, and draw the bundle .to smaller diameter while twisting to prevent excessive slipping of adjacent fibers past one another. These steps are necessary to secure adequate tenacity and uniformity. The cost and complexity of the process is markedly increased with the lighter denier yarns (e.g., cotton count greater than 30 cc.) used in making fine-textured wearing apparel fabrics. The higher cost is generally due to the necessity for obtaining greater uniformity of fibers in the smaller yarn bundle, the need for greater amounts of twist to secure adequate total yarn strength, and the fact that machine output is lower on a per-pound basis.

Although it has been known that yarn-like structures can be obtained by fibrillating highly oriented films, the products invariably obtained have been either too coarse or too weak to be useful Without further treatment for the production of high quality textile fabrics. In general, a high degree of fibrillation is required to obtain the fineness of structure necessary for high covering power and pleasing tactile properties. However, when films are fibrillated to this extent by conventional methods they generally lack sutficient strength to be handled by conventional textile machinery in normal fabric producing op erations, thus requiring that, following fibrillation of the film, some strength-imparting operation be carried out on the weak yarn. Typical strength-imparting steps such as twisting, as disclosed in U.S. 2,853,741, are expensive and are not needed to produce the yarns of this invention. It is an object of this invention to provide a process for preparing bulky yarns from molecularly oriented film strips. It is a further object of this invention to provide a bulky yarn having the aesthetic qualities and covering power of staple spun yarns, but characterized by substantially high strength, even at zero twist. It is another object of this invention to provide fine denier, essentially untwisted bulky yarns having the covering power, aesthetic qualities and general utility of comparable denier spun staple yarns. Another object of this invention is to provide a continuous process for the production of strong bulky yarns without the extrusion of continuous filaments or formation of staple fibers as an intermediate step, and without the necessity for spinning or twisting of filaments or yarns. Other objects and means for obtaining them will be apparent from the following disclosure.

In accordance with this invention, a fibrillatable film ribbon of a synthetic organic high molecular weight crystalline polymeric material which is molecularly oriented in its lengthwise direction, is passed through a zone of high turbulence provided by a high velocity jet or stream of air or other gas. Contact of successive portions of the film strip with the turbulent gas produces numerous longitudinal splits in the film ribbon to form a multifibrous, continuous two-dimensional network of fibrils, breaks some of the fibrils, and interlaces the fibrils to give a coherent yarn structure with a zero twist tenacity greater than 0.5 gram per denier. The product thus obtained is a bulky multifibrous yarn made up of fibrils which are of irregular length and have a trapezoidal cross section wherein the thin dimension is essentially the thickness of the original film strip. The fibrils are interconnected two-dimensionally at random points to form a cohesively unitary or one piece network structure. However, a considerable number of fibrils are detached on one end and protrude from the yarn bundle. The free ends are in most instances branched or flagellated.

Although the fibrils are in general coextensively oriented with the yarn axis, the dislocating force of the gas jet causes the fibrils to be interlaced, i.e., individually and collectively twisted, wrapped, intertwined and entangled. The interlacing is quite stable due to the high frictional constraint between adjacent fibrils of trapezoidal cross section, and consolidates and strengthens the yarn bundle. At random sites along the strand, the interlacing is so extensive that some fibrils wrap completely around the yarn bundle.

In addition to the interlaced configuration of the fibril network, a substantial number of the fibrils are convoluted into coils, loops, and whorls at random intervals along their length and at irregular spacings on dilferent fibrils. The convolutions exist in fibrils in the outer or peripheral layers of the yarn bundle and also in fibrils within the yarn bundle.

The convolutions are tiny, complete loops formed by a fibril doubling back upon itself, crossing itself, and then proceeding in substantially the original direction. In mathematics a curve of this type is said to have a crunode. Accordingly, the characteristic loops will be more specifically defined as crunodal loops, and loops of this type are intended, unless otherwise indicated in the following specification and claims. The majority of loops visible on the surface of the yarn are of a roughly circular shape and are properly described as ring-like. The crunodal loops inside of the yarn are not readily studied, but it is evident that the pressure of surrounding fibrils would tend to cause such loops to assume more complex shapes. At least 10 crunodal loops can be detected per lineal inch of strand in preferred embodiments.

The invention will be better understood by reference to the drawings. FIGURE 1 is a schematic representation of a film strip passing through a jet device (in section) suitable for operating the process of this invention. FIGURE 2 shows an end view of the jet device of FIG- URE 1. FIGURE 3 is a longitudinal schematic view of a unitary network yarn produced in accordance with this invention, showing fibril interlacing, flagellated free ends and crunodal loops. FIGURE 4 is a cross-sectional view of the yarn of FIGURE 3.

The flat cross-sectional configuration of the fibrils imparts remark-able stability to the interlacing and crunodal loops. Thus, the as-formed yarn of this invention, without .havingwheen twisted .or to alter the yarn structure, has a strong, coherent and stabilized bulky structure. The untwisted yarns of this invention-have a tenacity greater than 0.5 :gramper denier andare eminently suitedator direct use in ;the,preparation of high iquality fabrics by conventional textilermachinery.

The yarns of this invention have a covering power greater than conventionally textured continuous-filament yarns of the same total denierand same-number d indi vidual fiIa-m'entsas fibrils. h mayybe attributable primarilyto the flat or trapezoidal --cross section, since gen metrical considerations predictithat a flat shape has more periphery than-'a roundrshape whenibothwenclose' the same area. Thus,perunit weight, the strands ,ofthepieSent invention have =more sur-face area, hencemore Covering power, than comparable strands of the prior art. The improved coyering power maybe ascertained by -;tests --in is measured -microseopica1ly. .A -90-.denier staple ispun yarn with a l-3-eturn-s-per=inch ;Z-.twist has a diameter vof '5 mils, whereas a '90-denier, highly fibrillated yarn :of

same-157; 1' j subjectedetoanybther process f rploy-ed. The l requisite turbulence necessary in producing theeyarn product of this invention may be provided by a gas jet device similar to those shown in FIGURES 8, '9, 10, and 11 of US. 2,852,906, a simple embodiment of whichis showninFIGURES '11 and.2. V

Considerihgthe present invention in FIGURE 1, film strip/1 is fediat {a controlled rate by rollers 2 and 3 to jet devi'ce and passed through cylindricaljyarn passagepassage-way- 5. Rollers 7 and 8 vvay5 .Intercepting this passage-way-is gas entrance-way 6 with its .axis preferably intercepting the axis of yarn remove the yarn at a controlled rate from the vicinity of the jet device The 'aXis of entrance-way fi maybe perpendicular tothe axis .;which the'diameterlof the-.projectedvprofile 10f theiiyarn the present invention, given.sl3-turnsper inch aZ-tWiSt, V

has a' diameter of;7 mils. i The yarns of {this invention may *be 1 prepared in extremely smallgtot-al deniers.- Yarnsaof thisiinvention'can r be prepared having :cotton counts :as high :as 300. Spun of the exit point. *Forbest resultsythe change in direction should amount to or more"(with the angle measured yarns of thisfineness aret generallynnot obtainable fromsynthetic fibers. The .yarns are ;;sufficiently auniform to be -handled easily'by conventional machinery and to iform highly uniform fabrics ofrgood tactile properties without .the sacrifice of bulk-or fiber interlocking characteristics.

They can be usedwithout difliculty on' both -.automatic weaving and automatic knitting machines. Increased covering -'effectiveness; of fabrics -made with-this bulky product 7 permits the 3 production .of iabricfifrom": zsmaller .quantit'ies of yarn}- 'Becausegprocessing:requirements for "between emergent airstream and yarn take-oii direction"). "In'jsome instances,-'especially when increased amounts of 'interlacingareJdesired, it may be desirable tohave -'the fluid entrance' way aids tangent to thef circumference of the-strand passage way'channel so as to providegincreased twisting action ortorque upon the strandbeing'processed.

. Then-passageways in the 'apparatus, :namely, yarn passageeway orj'gas entrance way, may or may-not be of uniform cross section or cylindrical in shape; In cer- I Ttain instances-it maybe desirable to have o ne or another or thesepassageeways in theform of a right or obliqueconi'calfsectioninverted or otherwise, "andfor some appreparin films are not as: stringentgasthose'for :preparling filaments, the yarns of this invention can :ibelprep-ared th efpassageways'in' the from polymerswhich could not ,bereadily convertedinto yarns by prior art processes.

even at-zero twist, it is possible toretain'ibulkiness, even (at low :cotton counts, and -to vary hulk independently of 33 l the cotton counts. -It 'hascbeen necessary in 'the:pa:stto introduce :high twist ingo'rder. to j achieve qhigh cotton If higher tenacities are reunited, cthezyarnofithe present inventionicanrbe twisted. ln'thissevenn'zmuch lower twist is required for these yarns thanis required .to provide a comparable increase-in the strength of staple spun yarns.

plications'itjnay be desirable tojhave one or more of shape of a venturi orprovided with a constrictin g orifice. Many adaptations of the 'ap- .iparatus designed to-achieve arvarietypt-results will "be =S m ce-yarnsofthepresenttinvention,havezzhlgh' strength apparent, all being encompassed within the scope "of the invention. y 5

numb-1y, air 'isfutilized asfthe gas in carrying out the process "of this :invention, since this is the least, expensive 7 1 Other gases, such as nitrogen, carbon dioxide, steam, oxygen,i etc,"'may be used. The air pressure required to .carrygout thisprocess depends upon the 1 type of nozzle, the type of film, the film strip'speed and "the street desiredif Higher airpressures produce, with a The following table provides dataromparing the-effect 0f twist';on;the'itenacity of the productcof-Example-II;

with the effect of adding itwist .to .a conventional" staple yarn. :The strength iof' yarns fro n s taplei is substantially zero at zero atwist, iand :no comparison can be' p'rovided *belowiabout five turnsjper"inch;-'

crunodal loops and 2 extent {of} interlacing are determined given nozzle, liighergturbulenceinthe zone contacting the 'film estrip; "Increased turbulence results in increased fibrillation, i.e., smaller fibril widths and. greater numbers 55 tionjgenerally have an -average fibril width hetween,4 and lOOImierOn'sQand more'than 10 freefihril ends per inch 'of yarn, ,conditionsof 'high fibrillation produce average "fibril widths between 4" andf microns and free fibril uniformity, covering'powerand softness Although higher 'airpressuresithus'usuallyafford-preferredproducts, the

cost of compressing 'airfrnakes' it desirableto operate near jthe minimumpressure which" will" give adequate' per- .g'fo'rrnanc'e Higherflpressures' arealso required, for higher sn'and speeds, .buteconomics'favor higher speeds because :the air-costper poundof productdrops olfrapidly as gthe=throughputlis increased. Inusing-the gas jet device,

ebyrthendegree and-type ofiturbuleuceremployed in the iiibrillation process and (the; nature )iof: the film stripien;-

; suchasshown inFIGURE.1, gas pressures'of 5 to,80;p;s-.i.

, 7 V V V V W l V w I "The width or the fibrilsanumberiofrreerfibril ends, f

are employed.v a

1 "Excessive ipre'ssures :produce weak lor discontinuous --pr0du'cts. 'Itis desirableithat the air have a velocity beitween 30.5 and 1-L0 sonie velocity at the point of contact material be below 15 microns.

yarn strength and usefulness, the thickness should not be less than 1 micron.

5 the neighborhood of 500 to 1000 feet per second, the film ribbon speed should be less than one fifth of the air speed in order to promote adequate fibrillation and interlacing.

The film ribbon is fed into the jet at a faster rate than it is wound up downstream from the jet. A high degree of interlacing is promoted by maintaining the overfeed between 1 and 30%. Percent overfeed is defined as the excess in speed of the feed roll relative to the take-up roll divided by the speed of the take-up roll all multiplied by 100. For optimum performance overfeed should be high enough to prevent the strand from being pulled tight against the face of the jet after the strand makes the abrupt turn.

Fibrillatable films maybe made from any polymer capable of possessing an appreciable amount of crystallinity and which will retain orientation on relaxation after stretching. Some of the many crystalline polymers that can be used include: vinylidene chloride polymers; isotactic polystyrene; high density polyethylene; isotactic polypropylene; polyamides, such as poly(hexamethyleneadipamide), poly(ethylenesebacamide), poly(methylene bis p cyclohexyleneadipamide), polycaprolactam; polyesters, such as poly(ethylene terephthalate); and many others. Crystalline copolymers can also be used. Polyacrylonitrile and acrylonitrile copolymers with at least 85% acrylonitrile which appear to have only two dimensional crystallinity (i.e., a high degree of lateral order as seen by X-ray difiraction) for the purpose of this invention are classified as crystalline polymers.

'The polymers are formed by any suitable method into a film strip, which may be either a ribbon or thin hollow tube. They may be formed into wide films and then cut to the desired width. In order to obtain a film structure which is fibrillatable by the process of this invention to a continuous fibrillated bulky yarn, the film structures are drawn in the lengthwise direction to produce high unidirectional orientation. Fibrillating tendencies increase with increasing draw ratio and are most evident in drawn highly oriented film strips of crystalline polymer the orientation angle of which as measured by X-ray difiraction is less than 30. Drawing can be done as a separate step or can be done by a coupled extrusion and drawing operation. In order to afford fibrillated yarns of good uniformity and covering power by the process of this invention, it is essential that the thickness of the film strip However, for adequate Suitable widths for the drawn film str-ip range between inch and 1 inch. In order to obtain a cohesive integral strand which is interlaced three-dimensionally, it is "necessary to avoid the use of strips much wider than 1 inch.

The process of this invention is not limited to the formation of yarns from a single film strip. Two or more film strips may be used to build up a composite yarn of higher total denier from relatively thin film strips. Yarn of mixed composition may be formed by cofibrillation of film strips of diiferent polymeric compositions.

One particularly useful application is preparation of an antistatic yarn by cofibrillating with a single jet device film strips from polymers which develop opposite static charges. Similarly, one or more continuous-filament yarns may be subjected to the force of a single jet device together with one or more film strips. Heat treatments may be applied immediately before or during passage of the film strip through the jet to obtain heat-setting eifects which may aiford bulky, stretchy yarns with unusual hand or other novel properties.

' Suitable jets for use in this process are shown in Hall U.S. Patent 2,958,112 and in Breen U.S. Patent2,852,906, .FIGURES 1, 8, 9, 10, and 11.

The following examples illustrate specific embodiments of this invention. All parts and percentages are by weight unless otherwise indicated.

Example I A linear polyethylene having a melt index of 0.2 is dissolved in decahydronaphthalene to produce a solution containing about 10% of the polymer. This solution is cast at 160 C. on a glass plate using a 5-rnil doctor knife and dried at this temperature. The film strip obtained, which is approximately 0.5 mil thick and 0.87 inch wide, is drawn 12x at C. The resultant oriented film, which is approximately 0.1 mil thick and inch wide, is passed at approximately 30 feet per minute through the jet device shown in FIG. 1 wherein yarn passage-way 5 is inch in diameter and inch long, fiuid entranceway 6 is /s inch in diameter and inch long and forms an angle of 30 with passage-way 5. The jet is operated with air at a pressure of 5 pounds per square inch. The product obtained by this procedure is a multifibrous strand resembling a staple spun yarn. The yarn is a bulky, inte gral network of essentially longitudinally oriented random-length fibrils, having many flagellated ends along the length of the yarn. The fibrils have a trapezoidal cross section wherein the thickness is approximately 0.1 mil. Crunodal loops can be distinguished along the length of yarn. The yarn contains extensive fibril interlacing.

Following the above procedure, but using an air pressure of about 60 pounds per square inch, a yarn is obtained having an increased number of free ends and crunodal loops per inch of yarn.

Example 11 A 13% solution of polyacrylonitrile (inherent viscosity 1.4 in N,N-dimethylformamide) in N,N-dimethylformamide is cast at C. on a sheet of glass using a 4-mil doctor knife. After the solvent is removed, a film about 0.25 inch wide and 0.00035 inch thick is obtained. This film is removed from the glass sheet and drawn l2 over a hot plate at C. to produce an oriented film approximately 2.5 microns thick and 0.07 inch wide. This film strip is passed through the jet of Hall U.S. Patent 2,958,112 as shown in FIGS. 2-5 of that patent using an air pressure of 5 pounds per square inch. This jet comprises a straight-through passage for air and a side entry for yarn. The minimum throat diameter in the air passage of the jet is 0.076 inch. The side entry is fitted with a yarn tube which is a hollow needle as shown in the Hall patent. The yarn tube has an outside diameter of 0.042 inch and an inside diameter of 0.028 inch. The product is a bulky, 51-denier yarn made up of interconnected, longitudinally oriented, random length fibrils, each fibril being substantially trapezoidal in cross section wherein the long dimension averages 20 microns. There are about 20 loops per inch of yarn.

Following the same procedure as above but using an air pressure of 12.5 lbs/sq. in., a similar yarn is obtained having a tenacity of 1.3 grams per denier, about 40 loops and about 50 free ends per inch.

Optimum air pressure for processing the film of this example is about 20 lbs/sq. in. At higher pressures, greater flagellation of the fibrils accompanied by increased bulkiness is obtained at the expense of lower tenacities. At lower pressures there is less fiagellation accompanied by less bulkiness.

Example. III

A polyamide having an inherent viscosity of 1.35 in sulfuric acid and obtained by reacting m-phenylenediamine with isophthaloyl chloride is dissolved in N,N- dimethylacetamide containing a small amount of lithium chloride to obtain a solution containing 10% polymer. The solution is cast into a sheet at room temperature, using a 2 mil doctor knife, and the resulting film dried at: C. for 1 hour. The dried film sheet is drawn 5.5 X over a pin heated at 250 C., and the resulting oriented film is approximately 0.1 mil thick. Strips approximately 0.25 inch wide are cut from this film and passed through the jet device of Example II at an air pressure of about -ent gvisoosity or 1-;4 inj N;N dimethylformamide) an 15 lbs./sq in. There results abulky yarn comprising of 0.73 "in a '60/40 mixture'of itetrachloroethane and phenol is dissolved in trifluoroacetio acid to produce a solution of polymer. This solution is cast into a filmtusing .a. 2 mil doctor knifewatf5r0C.', and'theifilm V 1% inch s nfi t i i lm is drawn 5X at 80 C. to produce an oriented' hlm-approximate'1y'0.1 mil 'thick and V inch wide; ,Thisioriented'filmstripis fibrillated (formed into fibrils) in ac ,Hr'ied at thistemperature.) A

cordance with the procedure offExample 'II by passing.

Lthejsttipfthrough the'jet at aitjpressures va ying fl'omS to80 1bs'./sq.in. at feet per minute. A bulky product was obtained with about 'SO free ends/ineh,

V Example V A polyurethane having aninherent'viscosity of ,in 'm-c'reso l and obtained by reaction of 2-5. dimethylpiperlmixed'with'a solventicontaining 8; 8 partsot methylene 'chlorideand 12*parts formic acid; This admixture'is in turn dissolved in a 95/5 methylenechloride/formic acid mixture to produce 211070 solution of polymer. 'After casting this solutioninto a film at room temperature using a2'mil doctor knife, the resulting film is partially dried at room temperature and" then more thoroughly dried 'by maintaining at Cqfor 1 hour. The dried film is I 'drawn:4.5, "at 80?".Cfto produce anon'ented film with athickness of'approximatelyfld mil and a widtho'f 35 mils; Thisstrip is passed through thejiefdevice of 'Exampleil at a rate of about 1 5 feet per :-1' n'ir 1ute ,using 25 lbs/sq. 'in. The bullry yarn proan air pressure of -products (if the previous examples, has a zero twist "tenacity of "0.86 gram. per denier, a denier of j 1 30 and =about' 20lfree ends per inch; I J

' Ex p eyr diicedywhich is' similar inrvisual appearanceto'theibulky A ,copol ymer having an inherent viscosity of li;4 in

N;N-dimethylformamide. -and containing .94 parts "of gacrylonitrile and 6 parts .of methyl"acryliateisfdissolved :in N,'N-dimethy1formamide to-produce a solutifon containing 25% polymer. ThisQsolutionis extruded'through 1a sloti0.5 inch wide inchhigh'into, an aqueous; bath containing 52% by weight ZEN-dimethylfonmamide 50 at C. lAfter removaljoi"the solvent; the resulting wet film is drawn 9.x over a :surfacegheatedi to C.

" Fibrillation of the resulting' orientedfilmis accomplished --by passinga'strip'ofthefihn approximatelyQZ milithiek and 80 mils wide .through the: jet device ,of Example {'11 using an airpressure of ZOlbsQ/sqQjn; A'bulky yarh is sam v11 through 'a jetdevice' in accordance with the procedure of Example V1. The yarn 1 is similar visual appearance to those pro d'uced bythegprevious ,examplesand, ischaracterized by a denier of 1600, about (free ends and about 20' loops per iinch. 7

t 1. r I flmm e l A solution containing 17 by weight of polyacryl onitrile '(having -an-inherent viscos'ityof 1-;4 in*N;N-dib me'thyl-formamide) in NgN-dimethylformamijde is cast into a film'ati.l10 Cpusin 'g a'=2 0 mil doctor kn'ife; .A fter removing:the solvent from the film which'is-about lfi "inches wide and 0.002 inch thick, the filmis drawnfl8 -'in the; presence of steam at atmospheric pressure, The

film i-is passed -through an air jet device "similar 10 that jof Exarnp1e I but having a slig'htly'larger bore to accommodate' thelarger sizerfilm strip. t "Air pressure of 60 lbsz/sq; inis used; The product is a bulky yarn similar in' physical appearance to those produced by :the above proceduresbut having a tenacityof O.8 atzero"twist, a

denierof 2,000, andiabout 80crunodal loops per-inch.

xam li i {The "oriented filmv strip of Example V1 is given aitwist of '5 turns per 'inch'on 'a' conventional textile down :twister. This is fibrillated by passing the \twist'edi'film s ri ttaxs s i 9 1 .0 y-P-mnt he J t o E mp e L 'usingair at a pressureof 40 p. s'.i. Afterpassingthrough the jet, the product is-relaxed by passing over a'hot plate t 4 8. Them en e i u kyt m u tob dih a te ge t of 35 mm, p d njierziandan elongation. at

' h.i ;pmd 19 s woven n a br lo vfabric wh h ""showscovering power and uniformity superiorjtofthat obtained from spun yarns of the same polymer. 'IIn a di- 7 'tion, thesefabrics p'ossess soft, dry, silk-like tactile properfties which'arehighly desirahleiinfabrics'ffor uses such g shirrting and slips, The outstanding covering p'ower obtained by using these" bulky products is demonstrated {in ltnit'ted tri'cot ';fabrics,.1 which show light r'efiezztance 77%;vs.550%fto tco e qna ny on t i9t o jflie. same 1 eightQ Z /Ydi?) and lightitransmittancevof only 4:5%

fExample X of 3'turns per inch and fibrillatedybyraihs? p tgcessiof Exemph J L abi k iyiar i o t ine i h a d nie of .1900. ,A:threep ly;yar n 0155700 denier wasrmade from .thi s sample. The yarn v was tufted into a woven jute =-bi q i 1 to t rmt cutm l arpe c Eth i ilo n tsn fications: V i t r -hei {We-716',-

tbbtainedsimilar in'visual appearance tosthe bulky'prodtBakjn i e t yucts of the previous examples. This yarn has a tenacity a a v v -'-of"0.-9 gramperdenier at zero-twist, a denie -highla d -P --.-V- WW F Q W Q i i 7 about 15 'detcctable crunodal loopsperinch. *Ilheroiarpet showed-very{desirable'gfullness :ofnhand,

' Aim/admixture of olyacrylonitrile-Ihaving 'aninher- -tetramethylenex.s'ulfone is prepared' by spraying the tetramethylene; sulfone into-a: mechanicallystirred polyacrylo .nitri-le: powder; mixture is-milled '(rubber rnill), at i I .2009 v Cfgvvith .both: rollsgoperating at a i linear speed of .2273; feet per: minute, and the pla'stici zedpolynier noon- :hot wiater. AL AI inch Lstripof: the resulting 'iibrillatable iSfL-CDIWCIZid into: a -istrongfibulky 'yam -by V passing 1 {plied through 'the center 7 of the lgood 'fftuft :d'efinitionv ;;(resistance to intermingling gof ;]t fts).-; these;properties thesample is superiortto good ,qualityzwoolior nyloniilamfentgcarpetsrfi 1'21"; 1-

1 -"-Polyethy1ene terephthalatet polyi er with a relative -visi wf 3 13 e trude a ti 8 f w -ugh s ngu ar-di withiaidia'rneterof ozs ooinch and s1 w dths eruaol-o inch ate: rate of grains pe minu e.- Imp e- -vent collapse of the extrud'ed-ftubin g, nitrogen-w p- .,die @at a pressure of ap- P Ximately0lmiIIimeterofmercury, Immediately belowjthg die the ded tubingwas quenched-by'air flowat a linear speed of 145 y.p.m.

ing through a porous, sintered metal sleeve 19 millimeters in diameter and 65 millimeters in length. After leaving the quench sleeve the tubing was collapsed and drawn away by a set of pinch rolls 2% inches in diameter driven It was next passed to a conventional yarn windup bobbin also operating at 145 y.p.m. By suitably adjusting the nitrogen pressure within the tubing and the rate of flow of the quench air, a uniform, flattened tube was produced at any desired width up to about 5 millimeters and a corresponding doublewall thickness of about 5 microns or more.

The flattened tube was drawn 3.6x over a hot pin at 75 C. and then redrawn to a total of 4.5 X over a plate at 145 C. It was next twisted to turns per inch on a conventional textile downtwister, and passed through the air jet of Example 11 using a pressure of 17 p.s.i. to produce a bulky multifibrous yarn. The input speed of the flattened tube was 50 y.p.m., and the removal speed of the fibrillated product was 48.5 y.p.m., i.e., having an overfeed of 3.1%. A satisfactorily fibrillated yarn was also prepared from the drawn, untwisted ribbon. The bulky yarn was relaxed 6% by passing it over an 80 C. hot plate.

The final yarn thus prepared has a soft, pleasing hand with bulk and covering power equivalent or superior to that of spun yarn of the same polymer at the same denier. The yarn has a denier of 60, tenacity of 2.5 grams per denier, elongation 16%, and modulus of 60 grams per denier. Cross sections of the yarn show that there are about 50 individual ribbon-like fibrils in the yarn bundle ranging in width (or long dimension) from about 10 to 100 microns and about 5 microns in thickness. The yarn has improved aflinity for disperse dyes at room temperature in comparison with conventional multifilament yarns of the same polymer and having roughly the same filam'ent dimensions.

The novel process of this invention thus affords an economical route to the production of valuable textile yarns. Although it has been prevoiusly known that multifibrous strands could be produced from films, there has never been demonstrated a commercially feasible method for the production of strong, uniform, bulky strands of satisfactory covering power and tactile properties which can be directly employed in the manufacture of highquality textile fabrics. Air jet devices have been in commercial use for texturing or increasing the bulk of conventional yarns, but have never been employed on film 1% strips to produce the muitifibrous yarns of this invention.

This application is a continuation-in-part of application Serial No. 665,087, filed June 11, 1957, now abandoned and Serial No. 858,667, filed December 10, 1959.

What is claimed is:

1. A process for producing a bulky yarn of high covering power and good tactile properties comprising continuously contacting successive portions of a film strip of a synthetic organic high molecular weight crystalline polymer, molecularly oriented in the lengthwise direction of the strip, with a high velocity jet of gas to split the film strip along its length and form it into a bulky multifibrous yarn having substantial fibril interlacing and numerous free fibril ends along its length, and withdrawing the yarn from the gas jet.

2. The process of claim 1 wherein the film strip is a thin, hollow, collapsed tube.

3. The process of claim 1 wherein the jet velocity is between about 0.5 and 1.0 sonic velocity at the point of contact with the film strip.

4. The process of claim 1 wherein the air speed in the jet is between 500 and 1000 feet per second and the film strip speed is less than one fifth of the air speed.

5. The process of claim 1 wherein the film strip is fed into the jet at a faster rate than it is Wound up downstream from the jet, the overfeed being between 1 and 30%.

6. Th process of claim 1 wherein the film strip is between ,4 and 1 inch in width and below 15 microns in thickness.

7. The process of claim 1 wherein the film strip consists essentially of polyethylene.

8. The process of claim 1 wherein the film strip consists essentially of polyacrylonitrile.

9. The process of claim 1 wherein the film strip consists essentially of a polyarnide.

References Cited by the Examiner UN ITED STATES PATENTS 2,185,789 1/40 Jacque 28-1.4 2,920,349 1/60' White 28-14 2,948,927 8/60 Rasmussen 28- 1.4 3,003,304 10/61 Rasmussen 57157 MERVIN STEIN, Prinmry Exmniner.

DONALD W. PARKER, Examiner. 

1. A PROCESS FOR PRODUCILNG A BULKY YARN OF HIGH COVERING POWER AND GOOD TACTILE PROPERTIES COMPRISING CONTINUOUSLY CONTACTING SUCCESSIVE PORTIONS OF A FILM STRIP OF A SYNTHETIC ORGANIC HIGH MOLECULAR WEILGHT CRYSTALLINE POLYMER, MOLECULARLY ORIENTED IN THE LENGTHWISE DIRECTION OF THE STRIP, WITH A HIGH VELOCITY JET OF GAS TO SPLIT THE FILM STRIP ALONG ITS LENGTH AND FORM IT INTO A BULKY MULTIFIBROUS YARN HAVING SUBSTANTIAL FIBRIL INTERLACING AND NUMEROUS FREE FIBRIL ENDS ALONG ITS LENGTH, AND WITHDRAWING THE YARN FROM THE GAS JET. 